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performance-assessment
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Investigation of the performance of modified organic Rankine cycles (ORCs) and modified trilateral flash cycles (TFCs) assisted by a solar pond
, Article Solar Energy ; Volume 182 , 2019 , Pages 361-381 ; 0038092X (ISSN) ; Akbari, A ; Khalilian, M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Solar pond is a type of solar collector that stores solar energy in the form of heat. The solar pond can be used as a low-temperature heat source for electricity generation. In this paper, to find the most suitable power cycle for power generation from the solar pond, the performance of the Organic Rankine Cycle (ORC), Trilateral Flash Cycle (TFC) and their modified forms with an open feed liquid heater and an internal heat exchanger for different working fluids was investigated. Water was considered as the heat transfer fluid which transfers the stored heat from the solar pond to the working fluid of the cycle. The results indicate that in all cases, the energy and exergy efficiency of the...
Thermo-mechanical modeling of high speed spindles
, Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 282-293 ; 10263098 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
2012
Abstract
Prediction of the thermo-mechanical behavior of machine-tool spindles is essential in the reliable operation of high speed machine tools. In particular, the performance of these high speed spindles is dependent on their thermal behavior. The main source of heat generation in the spindle is the friction torque in angular contact ball bearings. This paper presents an effort to develop a comprehensive model of high speed spindles that includes viable models for the mechanical and thermal behavior of its major components, i.e., bearings, shaft and housing. Spindle housing and shaft are treated as six-degree-of-freedom Timoshenko beam elements. Bearings are modeled as two-node elements with five...
Stabilization of a vibrating non-classical micro-cantilever using electrostatic actuation
, Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 1824-1831 ; 10263098 (ISSN) ; Karami, F ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Sharif University of Technology
2013
Abstract
A closed-loop control methodology is investigated for stabilization of a vibrating non-classical micro-scale Euler-Bernoulli beam with nonlinear electrostatic actuation. The dimensionless form of governing nonlinear Partial Differential Equation (PDE) of the system is introduced. The Galerkin projection method is used to reduce the PDE of system to a set of nonlinear Ordinary Differential Equations (ODE). In non-classical micro-beams, the constitutive equations are obtained based on the non-classical continuum mechanics. In this work, proper control laws are constructed to stabilize the free vibration of non-classical micro-beams whose governing PDE is derived based on the modified strain...
Surrogate SDOF models for probabilistic performance assessment of multistory buildings: Methodology and application for steel special moment frames
, Article Engineering Structures ; Volume 212 , 2020 ; Mahsuli, M ; Ghannad, M. A ; Zareian, F ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper proposes a methodology for generating surrogate single-degree-of-freedom (SDOF) models that can be utilized to estimate the probability distribution of the roof drift ratio of multistory buildings at various ground motion intensity measures. The use of an SDOF model as a surrogate for multistory buildings can significantly alleviate the high computational cost for probabilistic seismic demand assessment considering both model uncertainty and record-to-record variability. The surrogate SDOF model generated herein explicitly accounts for model uncertainties and can be used as an alternative to the nonlinear dynamic analysis of detailed building structures. Applications for such...
Combined UV-C/H2O2-VUV processes for the treatment of an actual slaughterhouse wastewater
, Article Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes ; Volume 52, Issue 5 , 2017 , Pages 314-325 ; 03601234 (ISSN) ; Bustillo Lecompte, C. F ; Mehrvar, M ; Abdekhodaie, M. J ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
In this study, a three-factor, three-level Box-Behnken design with response surface methodology were used to maximize the TOC removal and minimize the H2O2 residual in the effluent of the combined UV-C/H2O2-VUV system for the treatment of an actual slaughterhouse wastewater (SWW) collected from one of the meat processing plants in Ontario, Canada. The irradiation time and the initial concentrations of total organic carbon (TOCo) and hydrogen peroxide (H2O2o) were the three predictors, as independent variables, studied in the design of experiments. The multiple response approach was used to obtain desirability response surfaces at the optimum factor settings. Subsequently, the optimum...
Quantification of seismic performance factors for ribbed bracing system
, Article Engineering Structures ; Volume 176 , 2018 , Pages 159-174 ; 01410296 (ISSN) ; Arzeytoon, A ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this investigation, seismic behavior and design coefficients of the ribbed bracing system (RBS) are evaluated by considering various archetypes that reflect configuration variability. RBS is a lateral bracing system with a unique mechanics that prevents buckling-induced damage by allowing free deformation of brace under compression. After successful experimental validation and numerical evaluation of RBS specimens in previous studies, FEMA P695 methodology is adopted in this study to subject 48 archetype structures to incremental dynamic analysis (IDA) procedure. Evaluation of the probabilistic collapse capacity of the archetypes against the code requirements reveals that RBS system can...
Prediction of stratified charge divided chamber engine performance
, Article Scientia Iranica ; Volume 16, Issue 1 , 2009 , Pages 92-100 ; 10263098 (ISSN) ; Mozafari, A ; Sharif University of Technology
2009
Abstract
Certain stratified charge divided chamber engines have a very small pre-chamber, equipped with a spark plug and a main chamber connected to the pre-chamber through nozzles, A theoretical model is presented in this research to predict ignition delay and initiation of combustion in the pre-chamber. It considers flame progress in the pre-chamber up to the point where the flame penetrates the main chamber through the connecting nozzles. Step by step calculations then continue in the main chamber and the mass fraction burned and the energy release rate are calculated. The process continues to the point where all the fuel is burned. At each step, due to a one degree rotation of the crank shaft,...
PH-responsive nanostructured polyaniline capsules for self-healing corrosion protection: the influence of capsule concentration
, Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 3512-3520 ; 10263098 (ISSN) ; Ghorbani, M ; Shojaei, A ; Mol, J. M. C ; Terryn, H ; Gonzalez Garcia, Y ; Sharif University of Technology
Abstract
Nanostructured hollow polyaniline (PANI) capsules are good candidates for encapsulation of corrosion inhibitors and pH-responsive release when incorporated into organic coatings. In previous studies, the corrosion protection performance of PANI capsules, containing organic inhibitor 2-Mercaptobenzothiazole (MBT), was demonstrated. The present work studies the influence of capsule concentrations (i.e., 0.3, 1, and 2 wt%) on the corrosion protection properties of the coating system. Anti-corrosion properties of different coatings were compared by means of Electrochemical Impedance Spectroscopy (EIS) and Scanning Vibrating Electrode Technique (SVET). MBT loaded PANI capsules in epoxy ester...
Performance of high-speed planing hulls accelerating from rest under the action of a surface piercing propeller and an outboard engine
, Article Applied Ocean Research ; Volume 77 , 2018 , Pages 45-60 ; 01411187 (ISSN) ; Najafi, S ; Amini, E ; Dashtimanesh, A ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this paper, a mathematical model for performance prediction of a high-speed planing hull in forward acceleration motion has been developed. Three degrees of freedom have been considered for solving the problem. Utilizing previous empirical equations of displacement ships, motion of the vessel in displacement regime has been simulated. In order to model pre-planing and planing regimes, 2D + T theory has been used. Equations for prediction of performance of a surface piercing propeller (SPP) and an engine have been presented. Validity of the proposed method has been assessed by comparing its results against previous experimental data, and good agreement between experimental and mathematical...
Marine hydrokinetic energy harvesting performance of diamond and square oscillators in tandem arrangements
, Article Energy ; Volume 202 , 2020 ; Esfehani, M. J ; Zeinoddini, M ; Naeeni, S. T. O ; Wu, J ; Shahvaghar Asl, S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The global demand for renewable energy sources has arisen significant research interests in marine hydrokinetic energy harvesting from flow induced vibrations. The current study deals with the hydrokinetic energy harvesting potentials of diamond and square oscillators at various inline configurations. Both the sharp edge sections and the wake induced vibrations in tandem arrangement can lead to galloping type of instability with high energy efficiency ratios. The present in-water towing tank experiments comprise 1DoF vibrating systems at Re ranging from 2 × 103 to 4.8 × 104. The results show that the upstream wake generally enhances the system efficiency and the mechanical work done by the...
Constrained single period problem under demand uncertainty
, Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1553-1563 ; 10263098 (ISSN) ; Shavandi, H ; Haji, R ; Sharif University of Technology
2011
Abstract
In this paper, we develop the multi-product, multi-constraint, Single Period Problem (SPP) with uncertain demands, considering an incremental discount situation. Three new models are presented for multi-product, multi-constraint SPP in fuzzy, stochastic and rough environments. We consider constraints, such as service rate, restriction on order quantity and restrictions on warehouse space and budget. We also consider that the order quantity is a multiplier of predefined batch size. Furthermore, three kinds of solution algorithm, (1) harmony search, (2) hybrid intelligent based on harmony search and fuzzy simulation and (3) hybrid intelligent based on harmony search and rough simulation, are...
An integrated dynamic model for evaluating the influence of ground to air heat transfer system on heating, cooling and CO2 supply in Greenhouses: Considering crop transpiration
, Article Renewable Energy ; Volume 173 , 2021 , Pages 42-56 ; 09601481 (ISSN) ; Roshandel, R ; Avami, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Nowadays, one of the most important challenges in developing greenhouses is meeting their energy demand. The other challenge is the high water consumption of evaporative-cooling systems in arid and semi-arid regions. In this study, a integrated dynamic model is developed to determine the greenhouse relative humidity, carbon dioxide, and temperature, considering transpiration. The model is applied to a greenhouse utilizing a ground to air heat transfer system, located in the Alborz province of Iran and the results are validated with experimental data. Energy and water performance of the greenhouse are evaluated for the case study greenhouse. Then, the model is applied to a greenhouse (similar...
Metal-organic framework derived NiSe2/CeO2nanocomposite as a high-performance electrocatalyst for oxygen evolution reaction (OER)
, Article Sustainable Energy and Fuels ; Volume 5, Issue 11 , 2021 , Pages 2994-3000 ; 23984902 (ISSN) ; Moravvej, S. H ; Moazzeni, M ; Akbarzadeh, E ; Sharif University of Technology
Royal Society of Chemistry
2021
Abstract
The development of efficient and cost-effective catalysts for the oxygen evolution reaction is highly desirable for applications that are based on sustainable and clean technologies. In this study, we report the synthesis of a series of cerium(iv) oxide and nickel diselenide nanocomposites (NiSe2/CeO2) as efficient electrocatalysts for the oxygen evolution reaction in an alkaline medium. The ratios of the two substances were optimized to reach the highest catalytic activity. The structure and morphology of synthesized materials were investigated by XRD, FE-SEM, EDX, BET, XPS, and TEM techniques. It was observed that the nanocomposite with a 10 : 1 mass ratio of NiSe2to CeO2showed the best...
Implementation of an optimal control strategy for a hydraulic hybrid vehicle using CMAC and RBF networks
, Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 327-334 ; 10263098 (ISSN) ; Foumani, M. S ; Boroushaki, M ; Sharif University of Technology
2012
Abstract
A control strategy on a hybrid vehicle can be implemented through different methods. In this paper, the Cerebellar Model Articulation Controller (CMAC) and Radial Basis Function (RBF) neural networks were applied to develop an optimal control strategy for a split parallel hydraulic hybrid vehicle. These networks contain a nonlinear mapping, and, also, the fast learning procedure has made them desirable for online control. The RBF network was constructed with the use of the K-mean clustering method, and the CMAC network was investigated for different association factors. Results show that the binary CMAC has better performance over the RBF network. Also, the hybridization of the vehicle...
Preparation and characterization of visible light sensitive nano titanium dioxide photocatalyst
, Article Scientia Iranica ; Volume 19, Issue 6 , December , 2012 , Pages 1626-1631 ; 10263098 (ISSN) ; Kazemeini, M ; Fattahi, M ; Sharif University of Technology
2012
Abstract
Dye sensitizers loaded on TiO2 decrease the electron excitation energy, thereby improving the photocatalytic performance by causing an increase in sensitivity under visible light irradiation. Three dye sensitizer precursors, Mordant Orange 1, N3 (red dye) and Cobalt (II) Phthalocyanine Tetrasulfonate (CoPcTs), were utilized to load the photocatalyst. The rate of the electron trapping process on platinum is clearly compatible with the migration rate of boundary electrons. Consequently, the migration of boundary electrons from the conduction band towards electron acceptors is increased by loading platinum onto the titanium dioxide. In this research, TiO2 was synthesized from a titanium...
The interface behavior of rock, conventional vibrated and roller compacted concrete
, Article Geotechnical and Geological Engineering ; Volume 38, Issue 2 , 2020 , Pages 1949-1969 ; Toufigh, V ; Ghaemian, M ; Sharif University of Technology
Springer
2020
Abstract
The interface behavior of rock and concrete and between layers of concrete highly affects the performance of concrete dam structures. In this investigation, a modified direct shear test was implemented in the laboratory to evaluate the interface behavior between (1) rock and conventional vibrated concrete (CVC), (2) rock and roller compacted concrete (RCC), (3) CVC and RCC and (4) two layers of RCC. Series of in situ shear tests were also performed between rock and concrete. The friction angle and cohesion for all tested interface were determined and analyzed. The effect of uniaxial compressive strength (UCS) of concrete on the interface behavior was determined. Additionally, the effect of...
Performance study of a supersonic inlet in the presence of a heat source
, Article Scientia Iranica ; Volume 18, Issue 3 B , 2011 , Pages 375-382 ; 10263098 (ISSN) ; Farahani, M ; Sepahi Younsi, J ; Sharif University of Technology
2011
Abstract
The flow over a supersonic inlet has been investigated experimentally and numerically at a free stream Mach number of 2 and a zero degree angle of attack. Wind tunnel tests were performed to obtain the performance parameters of the inlet and were used as a baseline and validation tools for the numerical code. A heat source was added to the flow field at a distance ahead of the inlet. The effect of heat source addition on the main performance parameters of the inlet is investigated numerically. Results show that the heat source considerably reduces drag coefficient; however, its effect on pressure recovery is not favorable. This unfavorable effect was then minimized by controlling heat source...
Dynamic performance enhancement of RC slabs by steel fibers vs. externally bonded GFRP sheets under impact loading
, Article Engineering Structures ; Volume 213 , 2020 ; Khaloo, A ; Sadraie, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Recently, to improve the dynamic behavior of Reinforced Concrete (RC) slabs under impact load, the methods of externally bonding Glass Fiber Reinforced Polymer (GFRP) sheets to slab and internally reinforcing concrete by steel fibers have been proposed. Nevertheless, it is required to investigate the comparison between these two methods on response of RC slabs under impact loads. In this study, the influence of volume fraction of steel fibers, the number of GFRP sheet layers (one or two) and the arrangement of GFRP sheets (covering the whole or parts of surface), are examined. Performance of fourteen 1000 × 1000 × 75 mm concrete slabs including one plain slab, one steel RC slab, three steel...
Phase II monitoring of binary response profiles
, Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 2238-2246 ; 10263098 (ISSN) ; Khedmati, M ; Mahlooji, H ; Sharif University of Technology
Sharif University of Technology
2013
Abstract
In many situations, the quality of a process can be characterized better by a relationship, known as a profile, between a response variable and one or more predictors. Almost all research efforts assume that response variable is continuous and follows a normal distribution, while there are instances in which the response is a binary variable, and methods such as logistic regression are commonly used. In this paper, four control schemes namely Hotelling T2, MEWMA, Likelihood Ratio Test (LRT) and LRT/EWMA are proposed to monitor binary response profiles in phase II. The performance of the proposed control charts is evaluated and compared by simulation experiments for different shift values in...
A new approach for bidding strategy of gencos using particles swarm optimization combined with simulated annealing method
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 31, Issue 3 , 2007 , Pages 303-315 ; 03601307 (ISSN) ; Ranjbar, A. M ; Bagheri Shouraki, S ; Shirani, A. R ; Sadati, N ; Sharif University of Technology
2007
Abstract
This paper describes a procedure that uses particle swarm optimization (PSO) combined with the simulated annealing (SA) to analyze the bidding strategy of Generating Companies (Gencos) in an electricity market where they have incomplete information about their opponents. In the proposed methodology, Gencos prepare their strategic bids according to the Supply Function Equilibrium (SFE) model and they change their bidding strategies until Nash equilibrium points are obtained. Nash equilibrium points constitute a central solution concept in the game theory and are computed with solving a global optimization problem. In this paper a new computational intelligence technique is introduced that can...